Centuries of looting had completely demolished the structure.

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The unfinished temple in a southern valley of the Lake Titicaca Basin in modern-day Bolivia has been a mystery for at least 500 years. Now known as the Pumapunku—"Door of the Jaguar" in the Quechua language—the complex stone structure is part of a sprawling complex of pyramids, plazas, and platforms built by a pre-Columbian culture we now call the Tiwanaku. Construction began around 500 CE and proceeded off and on, in phases, over the next few centuries until the Tiwanaku left the site around 900 or 1000 CE.

When the Inca Empire rose around 1200 CE, they claimed the sprawling ceremonial complex as the site of the world's creation, although they didn't finish the Tiwanaku's temple.

Old school and high tech

Spanish visitors in the 1500s and 1600s describe “a wondrous, though unfinished, building” with walls of H-shaped andesite pieces and massive gateways and windows carved from single blocks. These were set on remarkably smooth sandstone slabs, some of which weighed more than 80 tons. But after centuries of looting, the stones of the Pumapunku are so scattered that not one lies in its original place. The Tiwanaku left behind no written documents or plans to help modern researchers understand what their buildings looked like or what purpose they served.

Unlike the pottery and bone fragments archaeologists usually put back together, many of the scattered stones of Pumapunku weigh several tons—gluing them together in a sand tray wasn’t an option. So University of California, Berkeley archaeologist Alexei Vranich and his colleagues 3D-printed a scale model of nearly 150 carved andesite blocks in order to reconstruct part of the temple.

To make the high-tech solution work, Vranich had to turn to 19th-century archives for the measurements they needed to create accurate digital models of the stone blocks. Modern survey methods, like laser scanning, can produce incredibly detailed digital models of a site, right down to the subtleties of carvings or weathering on the surface of a stone block. But that actually turned out to be too much detail; the resulting files were much too large for site managers and local researchers in Bolivia to download and work with, since they often have limited Internet access and computer hardware.

Archaeologists didn’t even need most of that detail; they just needed simple geometric measurements, though they needed them to be very precise. So they turned to the field notes of past researchers. Most of those came from an expedition in the mid-1990s led by archaeologist J.P. Protzen, but for a few of the blocks, the team had to go all the way back to an 1848 expedition to find measurements.

Like LEGO for archaeologists

Vranich and his team added that data to a 3D modeling program called Sketchup, which they chose in part because it’s available in a free version. Then they 3D-printed the blocks with plaster powder at a four-percent scale. The whole process cost around $1,200; Vranich says using plastic filament would have been substantially cheaper, but plaster produced sharper angles and smoother edges, which were important as they tried to fit the pieces together. From there, they faced a long process of trial and error, like solving a large puzzle with blank pieces and no picture on the box.

Eventually those months of work paid off. Vranich and his colleagues say they’ve partially reconstructed the northern end of the Pumapunku and the general layout of the rest of the structure. The carved andesite gateways that gave the Pumapunku its modern name once stood in symmetrical lines, from 12.5 centimeter (4.9 inch) miniatures to 3 meter (9.8 feet) gateways carved from single, enormous blocks of stone. Facing one another, they probably created an optical illusion of infinite gateways stretching off into the distance.

Archaeologists used 3D-printed blocks to reconstruct part of the Pumapunku at 4-percent scale.

Vranich et al. 2018

3D printed blocks, with a cat for scale; he's helping.

Vranich et al. 2018

A model of the partially reconstructed Pumapunku.

Vranich et al. 2018

A gateway from the Pumapunku at 4-percent scale, reconstructed with 3D-printed blocks.

Vranich et al. 2018

The key turned out to be an elaborately carved andesite block called Model Stone 1, which turned out to be a scaled-down version of larger pieces of the building’s architecture. Researchers eventually fit Model Stone 1 together with several more scaled-down blocks, including a miniature gateway, and that provided a clue to the larger structure, with its symmetrical, repeating gateways.

Several of the stones are still missing, so it’s not likely that they’ll manage a complete reconstruction any time soon. But what they’ve pieced together so far actually bears a striking resemblance to buildings at earlier Tiwanaku sites in the area. That means archaeologists now have analogs to use for comparison in reconstructing other buildings at the site from the same period.

The future of archaeology?

Technology for digitally recording and modeling archaeological sites has improved dramatically in recent years, and some have suggested that the future of archaeology could mean refitting broken pieces of everything from potsherds to buildings on a computer screen rather than by hand. This could even mean automating the process, leaving it to an algorithm to match up broken edges into an intact whole. But the technology has so far turned out to be more cumbersome and less user-friendly than expected, and Vranich says that so far, there’s no easy substitute for an archaeologist’s trained eye.

“There may be a time in the future when ceramics and bone can be tossed on a surface, scanned, and automatically fitted, but until then, the human brain, under the right conditions, continues to be much faster and more efficient than computers when it comes to manipulating and visualizing irregular 3D forms,” he wrote.

The 3D files are available free online, where anyone can download and print them. Copies have been left with the site’s managers, where Vranich hopes they’ll be a useful tool in planning future research, preservation, and restoration efforts at Tiwanaku. They’re also accessible to the public, so citizen scientists can do their own trial and error and, perhaps, help piece together a little more of the site.

The geometric, symmetrical architecture at Tiwanaku makes it possible to digitally model the blocks with a few simple sets of measurements. Architecture from other cultures around the world might be a little harder to apply such methods to, but Vranich says it could still be useful at other sites.

"It is possible that using 3D printed models of fragments could help the study of other historic sites that have fallen apart in time, such as Angkor Wat in Cambodia, or that have been the victim of recent destruction, such as Palmyra in Syria,” Vranich said in a statement.

We could have reconstructed just using a 3D design program but we wanted to try something even more expensive than Legos.

There's plenty of benefit to doing something hands on when you're trying to lay out something that was done by hand a hundreds of years ago. A near lack of precision helps to better feel how a human would have done it.

I had to Google what CE was in terms of the years. We still very much use BC/AD here!

Spoiler: show

BCE - Before Common Era

CE - Common Era

Exactly the same as BC/AD without referencing Christ!

Edit: added spoiler

Quote:

Remember, this is B.C. ( mumbles). This was before the B.C./A.D. changeover,when everyone was going, “Is it A.D. yet?” ( mimes adjusting watch ) You didn't have to wind your watch back, you had to get a new bloody watch! “Oh, it’s A.D., isn’t it? Fucking ‘ell!” And the Muslim people going, "A.D? Who's he?"

I had to Google what CE was in terms of the years. We still very much use BC/AD here!

Spoiler: show

BCE - Before Common Era

CE - Common Era

Exactly the same as BC/AD without referencing Christ!

Edit: added spoiler

Quote:

Remember, this is B.C. ( mumbles). This was before the B.C./A.D. changeover,when everyone was going, “Is it A.D. yet?” ( mimes adjusting watch ) You didn't have to wind your watch back, you had to get a new bloody watch! “Oh, it’s A.D., isn’t it? Fucking ‘ell!” And the Muslim people going, "A.D? Who's he?"

Only Ethiopia doesn't use the Gregorian calendar, everyone is perfectly aware of AD/BC.

I had to Google what CE was in terms of the years. We still very much use BC/AD here!

Spoiler: show

BCE - Before Common Era

CE - Common Era

Exactly the same as BC/AD without referencing Christ!

Edit: added spoiler

Quote:

Remember, this is B.C. ( mumbles). This was before the B.C./A.D. changeover,when everyone was going, “Is it A.D. yet?” ( mimes adjusting watch ) You didn't have to wind your watch back, you had to get a new bloody watch! “Oh, it’s A.D., isn’t it? Fucking ‘ell!” And the Muslim people going, "A.D? Who's he?"

Only Ethiopia doesn't use the Gregorian calendar, everyone is perfectly aware of AD/BC.

Gung Hay Fat Choy! doesn't refer to January 1st, and I don't think the Chinese calendar marks AD/BC division. It's certainly true others are 'aware' of it, but they don't observe it. Did I misunderstand you? Sorry, if so.

I had to Google what CE was in terms of the years. We still very much use BC/AD here!

Spoiler: show

BCE - Before Common Era

CE - Common Era

Exactly the same as BC/AD without referencing Christ!

Edit: added spoiler

Quote:

Remember, this is B.C. ( mumbles). This was before the B.C./A.D. changeover,when everyone was going, “Is it A.D. yet?” ( mimes adjusting watch ) You didn't have to wind your watch back, you had to get a new bloody watch! “Oh, it’s A.D., isn’t it? Fucking ‘ell!” And the Muslim people going, "A.D? Who's he?"

Only Ethiopia doesn't use the Gregorian calendar, everyone is perfectly aware of AD/BC.

Gung Hay Fat Choy! doesn't refer to January 1st, and I don't think the Chinese calendar marks AD/BC division. It's certainly true others are 'aware' of it, but they don't observe it. Did I misunderstand you? Sorry, if so.

Apart from the small but significant point China uses the Gregorian calendar and has done so since 1912.

The carved andesite gateways that gave the Pumapunku its modern name once stood in symmetrical lines, from 12.5 centimeter (4.9 inch) miniatures to 3 meter (9.8 feet) gateways carved from single, enormous blocks of stone.

At 1/25th scale, that'd be 0.5cm for the smallest pieces, and 12cm for the largest.

The models were reduced, and several sizes were tested; the consensus reached was that 4% of the actual size provided the right size to easily handle in one hand while preserving details that were so painstakingly modeled. The printed pieces of andesite ranged in size from 15 by 11 cm for the Gateway of the Sun (original size 3.82 by 2.85 m) to 1.36 by 1.04 by .5 cm for the smallest piece representing an iconic doorway.

We could have reconstructed just using a 3D design program but we wanted to try something even more expensive than Legos.

Not by much.

Not at all

A rough estimate from the images shown, the plastic for ALL of those parts, and prototypes probably totaled less than $100

That mush Lego, especially any custom pieces would have been many times more expensive.

raxadian obviously doesnt have much experience with 3d printing.If the effort is spent to make a 3d model, then printing it is almost no additional effort.

Also, if you've ever tried to use something like SketchUp to, say, design a room layout, you'd know that rearranging objects in CAD programs is, at best, a tiresome and fiddly process. It also requires at least a little training in how to use the program. Rearranging blocks, on the other hand, is literally a skill that most people learn in their infancy, and is something that can be done quite quickly and easily. It also leverages our innate spatial-reasoning skills much better than a 2-dimensional representation of a 3-dimensional object on a screen can.

To make the high-tech solution work, Vranich had to turn to 19th-century archives for the measurements they needed to create accurate digital models of the stone blocks. Modern survey methods, like laser scanning, can produce incredibly detailed digital models of a site, right down to the subtleties of carvings or weathering on the surface of a stone block. But that actually turned out to be too much detail; the resulting files were much too large for site managers and local researchers in Bolivia to download and work with, since they often have limited Internet access and computer hardware.

Archaeologists didn’t even need most of that detail; they just needed simple geometric measurements, though they needed them to be very precise. So they turned to the field notes of past researchers. Most of those came from an expedition in the mid-1990s led by archaeologist J.P. Protzen, but for a few of the blocks, the team had to go all the way back to an 1848 expedition to find measurements.

What surprised me is that they had to go to the effort of digging through old records and re-creating the blocks from those measurements; couldn't they simply have down-sampled the high-resolution scans to something more manageable and then sent those to the site managers and local researchers instead?

Also, do you get upset when doctors say Metatarsophalangeal joint instead of toe knuckle?Then non-archaeologists should stop bitching when archaeologists use BCE/CE

I wasn't aware the author of this article was an archaeologist... There's no indication of that in the bio provided.

Nevertheless... While I understand, and generally agree, with your point - Ars is not an archaeological journal! If it were, it's likely that all persons reading it would have a common understanding of any specific terms as a result of a shared, or at least similar, background.

But Ars is a general news source - (albeit one with a science and technology focus) - which has readers of varying ages, nationalities, and educational and vocational backgrounds. As such, when a journalist(!) (which, regardless of any other educational or vocational background is what the author is serving as in this context) is describing something using a specific term - which is widely or commonly known by another term - it would be prudent for them to use the more common term. (Or, at least, explain the specific term in the context of the more common one). The fact that readers are complaining they had to resort to a Google search to understand something as fundamentally basic as a date shows that the author has failed to adequately inform her readers.

This is about Andean pre-Columbian architecture, not Mayan architecture.

It would have been concurrent with the middle part of the Mayan era , just half a continent away....

Great simplification, but no. The Tiwanaku and the Mayans were 4000km away, separated by jungle and mountain ranges, in a time when the best mode of transportation was by foot. Andean and Mesoamerican cultures have less in common than the Huns and the Franks did in the 5th century, since they too were "half a continent away" except they actually had a road connection and cultural trade. Cultures are not the same just because they share some genetics.

Also, do you get upset when doctors say Metatarsophalangeal joint instead of toe knuckle?Then non-archaeologists should stop bitching when archaeologists use BCE/CE

I wasn't aware the author of this article was an archaeologist... There's no indication of that in the bio provided.

Nevertheless... While I understand, and generally agree, with your point - Ars is not an archaeological journal! If it were, it's likely that all persons reading it would have a common understanding of any specific terms as a result of a shared, or at least similar, background.

But Ars is a general news source - (albeit one with a science and technology focus) - which has readers of varying ages, nationalities, and educational and vocational backgrounds. As such, when a journalist(!) (which, regardless of any other educational or vocational background is what the author is serving as in this context) is describing something using a specific term - which is widely or commonly known by another term - it would be prudent for them to use the more common term. (Or, at least, explain the specific term in the context of the more common one). The fact that readers are complaining they had to resort to a Google search to understand something as fundamentally basic as a date shows that the author has failed to adequately inform her readers.

Why should the author of the article need to be an archaeologist to use BCE/CE? The article is about archaeology. Would you insist that articles about scientific discoveries not use SI units as well? Should articles about technology omit needlessly technical terms like "bits" and "bytes" in favour of "ones or zeroes" and "eight ones or zeroes"?

Although even here I am being generous by admitting your (false) premise. BCE/CE is not exclusive to the field of archaeology, and has long since entered common usage.

As to your claim that "Ars is not an archaeological journal!" - a quick site search turns up 194 articles using the notation "BCE", dating back as far as 2004 CE. Articles about archaeology are a regular feature on Ars.

If you have managed to somehow go all this time without encountering "BCE/CE", well, bully for you. The good news is; you learnt something today.

The bad news is: although you seem to wish you'd been left to wallow contentedly in your own ignorance, neither Ars nor anyone else is obliged to indulge you in that desire.

We could have reconstructed just using a 3D design program but we wanted to try something even more expensive than Legos.

Not by much.

Not at all

A rough estimate from the images shown, the plastic for ALL of those parts, and prototypes probably totaled less than $100

That mush Lego, especially any custom pieces would have been many times more expensive.

raxadian obviously doesnt have much experience with 3d printing.If the effort is spent to make a 3d model, then printing it is almost no additional effort.

Also, if you've ever tried to use something like SketchUp to, say, design a room layout, you'd know that rearranging objects in CAD programs is, at best, a tiresome and fiddly process. It also requires at least a little training in how to use the program. Rearranging blocks, on the other hand, is literally a skill that most people learn in their infancy, and is something that can be done quite quickly and easily. It also leverages our innate spatial-reasoning skills much better than a 2-dimensional representation of a 3-dimensional object on a screen can.

To make the high-tech solution work, Vranich had to turn to 19th-century archives for the measurements they needed to create accurate digital models of the stone blocks. Modern survey methods, like laser scanning, can produce incredibly detailed digital models of a site, right down to the subtleties of carvings or weathering on the surface of a stone block. But that actually turned out to be too much detail; the resulting files were much too large for site managers and local researchers in Bolivia to download and work with, since they often have limited Internet access and computer hardware.

Archaeologists didn’t even need most of that detail; they just needed simple geometric measurements, though they needed them to be very precise. So they turned to the field notes of past researchers. Most of those came from an expedition in the mid-1990s led by archaeologist J.P. Protzen, but for a few of the blocks, the team had to go all the way back to an 1848 expedition to find measurements.

What surprised me is that they had to go to the effort of digging through old records and re-creating the blocks from those measurements; couldn't they simply have down-sampled the high-resolution scans to something more manageable and then sent those to the site managers and local researchers instead?

Re-read the article, some of the stones are no longer on site due to looting and no one knows where they are. There is literally no other option than the old original sources.